1. Field of the Invention
This invention relates to an ozone generating apparatus by utilizing silent discharge.
2. Description of the Related Art
Conventionally, many of ozone generating apparatuses used for water processing utilize silent discharge. The basic configuration of an ozone generating apparatuses utilizing silent discharge comprises a cylindrical dielectric tube having a metal film formed on an inner wall and a cylindrical metal tube, wherein the cylindrical dielectric tube is inserted into the cylindrical metal tube so as to have a predetermined gap between the inner wall of the metal tube and the outer wall of the dielectric tube. A raw material gas including oxygen such as air or oxygen gas is flowed in the gap, high alternating voltage is applied between the metal tube and the metal film, and an alternating current electric field is generated in the gap through the dielectric forming the dielectric tube. Accordingly, the raw material gas is discharged so as to generate ozone by ozonizing oxygen included in the raw material gas. In the ozone generating apparatuses having the above-mentioned configuration, various contrives are made such as providing an insulator in the vicinity of the end of a dielectric tube so as to prevent creeping discharge in the vicinity of the end of a dielectric tube and direct discharge between metals. (For example, Japanese Patent Application Laid Open No. 63-25203, Japanese Patent Application Laid Open No. 7-81904 and Japanese Patent Application Laid Open No. 10-338503).
Regarding ozone generating apparatuses used for processing large amount of water, following the increase of processing amount in recent years, it has been required for the apparatuses to increase processing amount without increasing the size of the apparatuses. In order to satisfy the above-mentioned requirement, it is necessary to increase the discharge power density so as to increase the amount of ozone generated per apparatus size. However, thermal troubles have been increased in response to an increase of discharge power density.